Emerging antibody combinations in oncology

Abstract

The use of monoclonal antibodies (mAbs) has become a general approach for specifically targeting and treating human disease. In oncology, the therapeutic utility of mAbs is usually evaluated in the context of treatment with standard of care, as well as other small molecule targeted therapies. Many anti-cancer antibody modalities have achieved validation, including the targeting of growth factor and angiogenesis pathways, the induction of tumor cell killing or apoptosis, and the blocking of immune inhibitory mechanisms to stimulate anti-tumor responses. But, as with other targeted therapies, few antibodies are curative because of biological complexities that underlie tumor formation and redundancies in molecular pathways that enable tumors to adapt and show resistance to treatment. This review discusses the combinations of antibody therapeutics that are emerging to improve efficacy and durability within a specific biological mechanism (e.g., immunomodulation or the inhibition of angiogenesis) and across multiple biological pathways (e.g., inhibition of tumor growth and induction of tumor cell apoptosis).

Figures and Tables

Figure 1 A schematic diagram of the major antigens and cell types where mAb combinations are being evaluated. These include the direct targeting of tumor cell antigens for reducing tumor growth/survival (receptor tyrosine kinases such as cMet, IGF-1R and the ErbB family members) and the direct targeting of tumor cell antigens for inducing intrinsic (death receptors, CD20) and extrinsic (CD20) mechanisms of tumor cell killing. Also included is the targeting of the tumor microenvironment and tumor stroma, such as the VEGF/VEGFR and the Ang2/Tie2 pathways for halting tumor angiogenesis. Finally, also illustrated is the targeting of cell surface antigens (e.g., CTLA-4, PD-1) on lymphocytes to enable a patient to overcome or reverse tumor-induced suppression of their own natural immune surveillance for abnormal cell growth (also known as immunomodulatory approaches).

Figure 2 Bar diagram of the escalation in mAb combination publications over the last decade. The publication numbers came directly from our bibliography and not from specific key word searches within PubMed.

Table 1 RTK, angiogenesis and RTK/angiogenesis mAb combinations in clinical trials

Table 2 Immunomodulatory and B-cell targeted mAb combinations in clinical trials